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Juan Adánez - One of the best experts on this subject based on the ideXlab platform.
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Coal combustion via Chemical Looping assisted by Oxygen Uncoupling with a manganese‑iron mixed oxide doped with titanium
Fuel Processing Technology, 2020Co-Authors: Raúl Pérez-vega, Francisco García-labiano, Pilar Gayán, Alberto Abad, Maria Izquierdo, Luis F. De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion allows the carbon dioxide capture by using an oxygen carrier, which transports the oxygen required for combustion from the Air to the fuel. But complete combustion of a solid fuel is not achieved when low cost materials were used as oxygen carriers. Manganese‑iron mixed oxide doped with titanium has been identified as a promising oxygen carrier to improve combustion efficiency due to its oxygen uncoupling capability. The objective of this work was to assess the potential of this oxygen carrier when burning coal in a chemical looping unit. The coal combustion efficiency and carbon dioxide capture were evaluated as a function of the operating conditions both in the fuel and Air Reactor. Carbon dioxide capture was affected by the solids residence time in the fuel Reactor. Coal combustion efficiency increased as the oxygen uncoupling capability was enhanced by using suitable operating conditions in the Air Reactor. Almost full coal combustion (99.4%) was achieved by setting an Air Reactor temperature of 880 °C, an Air excess of 1.8, a fuel Reactor temperature of 925 °C, and an oxygen carrier to fuel ratio >3. The oxygen carrier showed magnetic properties, allowing its re-use after being separated from ash.
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Chemical Looping Combustion of biomass: CLOU experiments with a Cu-Mn mixed oxide
Fuel Processing Technology, 2018Co-Authors: I. Adánez-rubio, Francisco García-labiano, Pilar Gayán, Alberto Abad, T. Mendiara, Maria Izquierdo, Antón Pérez-astray, Luis F. De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion (CLC) is a low-cost CO 2 capture technology with a low energy penalty. Bio-energy with CO 2 capture and storage (BECCS) opens up the possibility for negative CO 2 emissions involving the removal of CO 2 already emitted into the atmosphere. The oxygen needed for combustion in CLC processes is supplied by a solid oxygen carrier circulating between the fuel Reactor and the Air Reactor. In this work, the combustion of different types of biomass, such as pine sawdust, olive stones and almond shells, was studied in a continuous 1.5 kW th CLC unit. A mixed Cu-Mn oxide was used as the oxygen carrier. This material releases gaseous oxygen when reduced, resulting in Chemical looping combustion with oxygen uncoupling (CLOU). The released oxygen reacts with both the volatiles and char generated inside the fuel Reactor when biomass is fed into it. The oxygen carrier is reoxidized in Air inside the Air Reactor. High CO 2 capture and 100% combustion efficiencies were achieved with this Cu-Mn oxygen carrier. The oxygen concentration inside the Air Reactor did not affect CO 2 capture efficiency under the studied conditions.
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Coal combustion with a spray granulated Cu-Mn mixed oxide for the Chemical Looping with Oxygen Uncoupling (CLOU) process
Applied Energy, 2017Co-Authors: Iñaki Adánez-rubio, Francisco García-labiano, Pilar Gayán, Alberto Abad, Luis F. De Diego, Juan AdánezAbstract:Abstract The Chemical Looping with Oxygen Uncoupling (CLOU) process is a form of Chemical Looping Combustion (CLC) technology that enables the combustion of solid fuels by means of oxygen carriers that release gaseous oxygen in the fuel Reactor, i.e. with oxygen uncoupling capability. In recent years, tests have found several Cu-based, Mn-based and mixed oxide oxygen carriers with suitable properties for the CLOU process. Among them, Cu-Mn mixed oxides show high reactivity and high O2 equilibrium concentration at temperatures of interest for coal combustion. In this work, proof of concept was demonstrated by burning coal with Cu-Mn mixed oxides in a 1.5 kWth CLOU unit for the first time. The effect of fuel Reactor temperature, solids circulation flow, fluidization agent in the fuel Reactor (inert N2 or steam as gasifying agent), and excess Air in the Air Reactor on combustion efficiency and CO2 capture rate was analysed. The results showed that high combustion efficiency and CO2 capture are feasible using this material at relatively low fuel Reactor operating temperatures. Therefore, the developed Cu-Mn mixed oxide was a suitable material for use as an oxygen carrier for the CLOU combustion of solid fuels. Optimum operating conditions were determined for this oxygen carrier with regard to the oxygen circulation rate and Air Reactor conditions for the regeneration of the oxygen carrier.
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Sulphur, nitrogen and mercury emissions from coal combustion with CO2 capture in chemical looping with oxygen uncoupling (CLOU)
International Journal of Greenhouse Gas Control, 2016Co-Authors: Raúl Pérez-vega, Francisco García-labiano, Pilar Gayán, Alberto Abad, Maria Izquierdo, Luis F. De Diego, Iñaki Adánez-rubio, Juan AdánezAbstract:Abstract Chemical looping with oxygen uncoupling (CLOU) is a chemical looping combustion (CLC) process for the combustion of solid fuels with the use of a solid oxygen carrier that releases gaseous oxygen inside the fuel Reactor. The aim of this work was to study the fate of pollutant elements present in fuel, i.e. S, N and Hg, during CLOU combustion. Experiments using lignite as fuel were carried out in a 1.5 kW th unit operating continuously for more than 35 h of coal combustion. Novel particles containing 50 wt.% CuO, 10 wt.% Fe 2 O 3 and 40 wt.% MgAl 2 O 4 prepared by spray drying were used as the oxygen carriers in the CLOU process. Most of the sulphur introduced with the fuel exited as SO 2 at the fuel Reactor outlet, although a small amount of SO 2 was measured at the Air Reactor outlet. Most of the nitrogen present in coal was found as N 2 at the outlet of the fuel Reactor, although 20 wt.% of N in the coal was converted to NO. Mercury speciation was also analyzed. The major mercury species in the fuel Reactor was Hg 0 (g), and the Hg 0 (g)/Hg total (g) ratio in the Air Reactor was 0.5.
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Mercury Release and Speciation in Chemical Looping Combustion of Coal
Energy & Fuels, 2014Co-Authors: T. Mendiara, Francisco García-labiano, Pilar Gayán, Alberto Abad, Maria Izquierdo, L.f. De Diego, Juan AdánezAbstract:In the in situ Gasification Chemical Looping Combustion of coal (iG-CLC), the fuel is gasified in situ in the fuel Reactor and gasification products are converted to CO2 and H2O by reaction with the oxygen carrier. This work is the first study on mercury release in Chemical Looping Combustion of coal. The determination of mercury speciation (Hg0/Hg2+) in fuel and Air Reactors as well as the quantification of the amount of mercury released in each Reactor were addressed for the first time. The fraction of the mercury in coal vaporized in the fuel Reactor depended mainly on the fuel Reactor temperature and the coal type. In the fuel Reactor, mercury was mainly emitted as Hg0 in the gas phase and the amount increased with the temperature. In the Air Reactor, mercury was mostly emitted as Hg2+. In a real CLC system, mercury emissions to the atmosphere will decrease compared to conventional combustion as only mercury released in the Air Reactor will reach the atmosphere. However, measures should be taken to re...
Alberto Abad - One of the best experts on this subject based on the ideXlab platform.
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Coal combustion via Chemical Looping assisted by Oxygen Uncoupling with a manganese‑iron mixed oxide doped with titanium
Fuel Processing Technology, 2020Co-Authors: Raúl Pérez-vega, Francisco García-labiano, Pilar Gayán, Alberto Abad, Maria Izquierdo, Luis F. De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion allows the carbon dioxide capture by using an oxygen carrier, which transports the oxygen required for combustion from the Air to the fuel. But complete combustion of a solid fuel is not achieved when low cost materials were used as oxygen carriers. Manganese‑iron mixed oxide doped with titanium has been identified as a promising oxygen carrier to improve combustion efficiency due to its oxygen uncoupling capability. The objective of this work was to assess the potential of this oxygen carrier when burning coal in a chemical looping unit. The coal combustion efficiency and carbon dioxide capture were evaluated as a function of the operating conditions both in the fuel and Air Reactor. Carbon dioxide capture was affected by the solids residence time in the fuel Reactor. Coal combustion efficiency increased as the oxygen uncoupling capability was enhanced by using suitable operating conditions in the Air Reactor. Almost full coal combustion (99.4%) was achieved by setting an Air Reactor temperature of 880 °C, an Air excess of 1.8, a fuel Reactor temperature of 925 °C, and an oxygen carrier to fuel ratio >3. The oxygen carrier showed magnetic properties, allowing its re-use after being separated from ash.
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Life cycle assessment of natural gas fuelled power plants based on chemical looping combustion technology
Energy Conversion and Management, 2019Co-Authors: Alberto Navajas, Francisco García-labiano, Alberto Abad, T. Mendiara, Víctor Goñi, Adrián Jiménez, Luis M. Gandía, Luis F. De DiegoAbstract:Abstract Among the different Carbon Capture and Storage (CCS) technologies being developed in the last decades, Chemical Looping Combustion (CLC) stands out since it allows inherent CO2 capture. In the CLC process, there is a solid oxygen carrier circulating between two Reactors in a cycle that allows providing the oxygen needed for combustion. In one of the Reactors, named as fuel Reactor, the fuel is introduced and combusted while the oxygen carrier reduction takes place. In the second Reactor, named Air Reactor, the oxygen carrier is reoxidized in Air. Different materials based on copper, nickel and iron oxides have been proposed as oxygen carriers for the CLC process. This work presents an environmental evaluation of the CLC process for natural gas based on Life Cycle Assessment (LCA). Five different oxygen carrier materials already tested in pilot plants were considered and the results compared to the conventional natural gas combustion in a gas turbine in a combined cycle without and with CO2 capture using postcombustion capture with amines. In view of the results, lower impact of the CLC process compared to the base case is expected without and with CO2 capture. The influence of several variables on the results was considered, such as temperature in the Air Reactor, lifetime of the oxygen carrier and possibility of recuperation of the depleted oxygen carrier. The nickel-based oxygen carriers were identified as the most adequate to be used in natural gas combustion. However, due to their toxicity, several analyses were also performed in order to identify improvements in the known oxygen carriers that can qualify them to replace nickel-based materials.
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Chemical Looping Combustion of biomass: CLOU experiments with a Cu-Mn mixed oxide
Fuel Processing Technology, 2018Co-Authors: I. Adánez-rubio, Francisco García-labiano, Pilar Gayán, Alberto Abad, T. Mendiara, Maria Izquierdo, Antón Pérez-astray, Luis F. De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion (CLC) is a low-cost CO 2 capture technology with a low energy penalty. Bio-energy with CO 2 capture and storage (BECCS) opens up the possibility for negative CO 2 emissions involving the removal of CO 2 already emitted into the atmosphere. The oxygen needed for combustion in CLC processes is supplied by a solid oxygen carrier circulating between the fuel Reactor and the Air Reactor. In this work, the combustion of different types of biomass, such as pine sawdust, olive stones and almond shells, was studied in a continuous 1.5 kW th CLC unit. A mixed Cu-Mn oxide was used as the oxygen carrier. This material releases gaseous oxygen when reduced, resulting in Chemical looping combustion with oxygen uncoupling (CLOU). The released oxygen reacts with both the volatiles and char generated inside the fuel Reactor when biomass is fed into it. The oxygen carrier is reoxidized in Air inside the Air Reactor. High CO 2 capture and 100% combustion efficiencies were achieved with this Cu-Mn oxygen carrier. The oxygen concentration inside the Air Reactor did not affect CO 2 capture efficiency under the studied conditions.
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Coal combustion with a spray granulated Cu-Mn mixed oxide for the Chemical Looping with Oxygen Uncoupling (CLOU) process
Applied Energy, 2017Co-Authors: Iñaki Adánez-rubio, Francisco García-labiano, Pilar Gayán, Alberto Abad, Luis F. De Diego, Juan AdánezAbstract:Abstract The Chemical Looping with Oxygen Uncoupling (CLOU) process is a form of Chemical Looping Combustion (CLC) technology that enables the combustion of solid fuels by means of oxygen carriers that release gaseous oxygen in the fuel Reactor, i.e. with oxygen uncoupling capability. In recent years, tests have found several Cu-based, Mn-based and mixed oxide oxygen carriers with suitable properties for the CLOU process. Among them, Cu-Mn mixed oxides show high reactivity and high O2 equilibrium concentration at temperatures of interest for coal combustion. In this work, proof of concept was demonstrated by burning coal with Cu-Mn mixed oxides in a 1.5 kWth CLOU unit for the first time. The effect of fuel Reactor temperature, solids circulation flow, fluidization agent in the fuel Reactor (inert N2 or steam as gasifying agent), and excess Air in the Air Reactor on combustion efficiency and CO2 capture rate was analysed. The results showed that high combustion efficiency and CO2 capture are feasible using this material at relatively low fuel Reactor operating temperatures. Therefore, the developed Cu-Mn mixed oxide was a suitable material for use as an oxygen carrier for the CLOU combustion of solid fuels. Optimum operating conditions were determined for this oxygen carrier with regard to the oxygen circulation rate and Air Reactor conditions for the regeneration of the oxygen carrier.
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1 Effect of operating conditions in Chemical-Looping Combustion of coal in a 500 Wth unit
2016Co-Authors: Ana Cuadrat, Francisco García-labiano, Pilar Gayán, Alberto Abad, Diego Juan AdánezAbstract:Chemical-Looping Combustion, CLC, is one of the most promising processes to capture CO2 at a low cost. It is based on the transfer of the oxygen from Air to the fuel by using a solid oxygen-carrier that circulates between two interconnected fluidized-bed Reactors: the fuel- and the Air-Reactor. The CO2 capture is inherent to this process, as the Air does not get mixed with the fuel. In this work, the CLC technology with coal was investigated in a continuous 500 Wth rig using ilmenite as oxygen-carrier. The plant was basically composed of two interconnected fluidized-bed Reactors, a riser for solids transport from the Air- to the fuel-Reactor, a solid valve to control the flow rate of solids fed to the fuel-Reactor and a cyclone. A Colombian bituminous coal is fed by a screw feeder at the bottom of the bed. In the fuel-Reactor the oxygen-carrier is reduced by the volatile matter and gasification products of coal. Reduced oxygen-carrier particles were led to the Air-Reactor where they were re-oxidized and got ready to start a new cycle. This work is focused on the study of the fuel-Reactor within the process. The behaviour of th
Pilar Gayán - One of the best experts on this subject based on the ideXlab platform.
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Coal combustion via Chemical Looping assisted by Oxygen Uncoupling with a manganese‑iron mixed oxide doped with titanium
Fuel Processing Technology, 2020Co-Authors: Raúl Pérez-vega, Francisco García-labiano, Pilar Gayán, Alberto Abad, Maria Izquierdo, Luis F. De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion allows the carbon dioxide capture by using an oxygen carrier, which transports the oxygen required for combustion from the Air to the fuel. But complete combustion of a solid fuel is not achieved when low cost materials were used as oxygen carriers. Manganese‑iron mixed oxide doped with titanium has been identified as a promising oxygen carrier to improve combustion efficiency due to its oxygen uncoupling capability. The objective of this work was to assess the potential of this oxygen carrier when burning coal in a chemical looping unit. The coal combustion efficiency and carbon dioxide capture were evaluated as a function of the operating conditions both in the fuel and Air Reactor. Carbon dioxide capture was affected by the solids residence time in the fuel Reactor. Coal combustion efficiency increased as the oxygen uncoupling capability was enhanced by using suitable operating conditions in the Air Reactor. Almost full coal combustion (99.4%) was achieved by setting an Air Reactor temperature of 880 °C, an Air excess of 1.8, a fuel Reactor temperature of 925 °C, and an oxygen carrier to fuel ratio >3. The oxygen carrier showed magnetic properties, allowing its re-use after being separated from ash.
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Chemical Looping Combustion of biomass: CLOU experiments with a Cu-Mn mixed oxide
Fuel Processing Technology, 2018Co-Authors: I. Adánez-rubio, Francisco García-labiano, Pilar Gayán, Alberto Abad, T. Mendiara, Maria Izquierdo, Antón Pérez-astray, Luis F. De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion (CLC) is a low-cost CO 2 capture technology with a low energy penalty. Bio-energy with CO 2 capture and storage (BECCS) opens up the possibility for negative CO 2 emissions involving the removal of CO 2 already emitted into the atmosphere. The oxygen needed for combustion in CLC processes is supplied by a solid oxygen carrier circulating between the fuel Reactor and the Air Reactor. In this work, the combustion of different types of biomass, such as pine sawdust, olive stones and almond shells, was studied in a continuous 1.5 kW th CLC unit. A mixed Cu-Mn oxide was used as the oxygen carrier. This material releases gaseous oxygen when reduced, resulting in Chemical looping combustion with oxygen uncoupling (CLOU). The released oxygen reacts with both the volatiles and char generated inside the fuel Reactor when biomass is fed into it. The oxygen carrier is reoxidized in Air inside the Air Reactor. High CO 2 capture and 100% combustion efficiencies were achieved with this Cu-Mn oxygen carrier. The oxygen concentration inside the Air Reactor did not affect CO 2 capture efficiency under the studied conditions.
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Coal combustion with a spray granulated Cu-Mn mixed oxide for the Chemical Looping with Oxygen Uncoupling (CLOU) process
Applied Energy, 2017Co-Authors: Iñaki Adánez-rubio, Francisco García-labiano, Pilar Gayán, Alberto Abad, Luis F. De Diego, Juan AdánezAbstract:Abstract The Chemical Looping with Oxygen Uncoupling (CLOU) process is a form of Chemical Looping Combustion (CLC) technology that enables the combustion of solid fuels by means of oxygen carriers that release gaseous oxygen in the fuel Reactor, i.e. with oxygen uncoupling capability. In recent years, tests have found several Cu-based, Mn-based and mixed oxide oxygen carriers with suitable properties for the CLOU process. Among them, Cu-Mn mixed oxides show high reactivity and high O2 equilibrium concentration at temperatures of interest for coal combustion. In this work, proof of concept was demonstrated by burning coal with Cu-Mn mixed oxides in a 1.5 kWth CLOU unit for the first time. The effect of fuel Reactor temperature, solids circulation flow, fluidization agent in the fuel Reactor (inert N2 or steam as gasifying agent), and excess Air in the Air Reactor on combustion efficiency and CO2 capture rate was analysed. The results showed that high combustion efficiency and CO2 capture are feasible using this material at relatively low fuel Reactor operating temperatures. Therefore, the developed Cu-Mn mixed oxide was a suitable material for use as an oxygen carrier for the CLOU combustion of solid fuels. Optimum operating conditions were determined for this oxygen carrier with regard to the oxygen circulation rate and Air Reactor conditions for the regeneration of the oxygen carrier.
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1 Effect of operating conditions in Chemical-Looping Combustion of coal in a 500 Wth unit
2016Co-Authors: Ana Cuadrat, Francisco García-labiano, Pilar Gayán, Alberto Abad, Diego Juan AdánezAbstract:Chemical-Looping Combustion, CLC, is one of the most promising processes to capture CO2 at a low cost. It is based on the transfer of the oxygen from Air to the fuel by using a solid oxygen-carrier that circulates between two interconnected fluidized-bed Reactors: the fuel- and the Air-Reactor. The CO2 capture is inherent to this process, as the Air does not get mixed with the fuel. In this work, the CLC technology with coal was investigated in a continuous 500 Wth rig using ilmenite as oxygen-carrier. The plant was basically composed of two interconnected fluidized-bed Reactors, a riser for solids transport from the Air- to the fuel-Reactor, a solid valve to control the flow rate of solids fed to the fuel-Reactor and a cyclone. A Colombian bituminous coal is fed by a screw feeder at the bottom of the bed. In the fuel-Reactor the oxygen-carrier is reduced by the volatile matter and gasification products of coal. Reduced oxygen-carrier particles were led to the Air-Reactor where they were re-oxidized and got ready to start a new cycle. This work is focused on the study of the fuel-Reactor within the process. The behaviour of th
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Sulphur, nitrogen and mercury emissions from coal combustion with CO2 capture in chemical looping with oxygen uncoupling (CLOU)
International Journal of Greenhouse Gas Control, 2016Co-Authors: Raúl Pérez-vega, Francisco García-labiano, Pilar Gayán, Alberto Abad, Maria Izquierdo, Luis F. De Diego, Iñaki Adánez-rubio, Juan AdánezAbstract:Abstract Chemical looping with oxygen uncoupling (CLOU) is a chemical looping combustion (CLC) process for the combustion of solid fuels with the use of a solid oxygen carrier that releases gaseous oxygen inside the fuel Reactor. The aim of this work was to study the fate of pollutant elements present in fuel, i.e. S, N and Hg, during CLOU combustion. Experiments using lignite as fuel were carried out in a 1.5 kW th unit operating continuously for more than 35 h of coal combustion. Novel particles containing 50 wt.% CuO, 10 wt.% Fe 2 O 3 and 40 wt.% MgAl 2 O 4 prepared by spray drying were used as the oxygen carriers in the CLOU process. Most of the sulphur introduced with the fuel exited as SO 2 at the fuel Reactor outlet, although a small amount of SO 2 was measured at the Air Reactor outlet. Most of the nitrogen present in coal was found as N 2 at the outlet of the fuel Reactor, although 20 wt.% of N in the coal was converted to NO. Mercury speciation was also analyzed. The major mercury species in the fuel Reactor was Hg 0 (g), and the Hg 0 (g)/Hg total (g) ratio in the Air Reactor was 0.5.
Luis F. De Diego - One of the best experts on this subject based on the ideXlab platform.
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Coal combustion via Chemical Looping assisted by Oxygen Uncoupling with a manganese‑iron mixed oxide doped with titanium
Fuel Processing Technology, 2020Co-Authors: Raúl Pérez-vega, Francisco García-labiano, Pilar Gayán, Alberto Abad, Maria Izquierdo, Luis F. De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion allows the carbon dioxide capture by using an oxygen carrier, which transports the oxygen required for combustion from the Air to the fuel. But complete combustion of a solid fuel is not achieved when low cost materials were used as oxygen carriers. Manganese‑iron mixed oxide doped with titanium has been identified as a promising oxygen carrier to improve combustion efficiency due to its oxygen uncoupling capability. The objective of this work was to assess the potential of this oxygen carrier when burning coal in a chemical looping unit. The coal combustion efficiency and carbon dioxide capture were evaluated as a function of the operating conditions both in the fuel and Air Reactor. Carbon dioxide capture was affected by the solids residence time in the fuel Reactor. Coal combustion efficiency increased as the oxygen uncoupling capability was enhanced by using suitable operating conditions in the Air Reactor. Almost full coal combustion (99.4%) was achieved by setting an Air Reactor temperature of 880 °C, an Air excess of 1.8, a fuel Reactor temperature of 925 °C, and an oxygen carrier to fuel ratio >3. The oxygen carrier showed magnetic properties, allowing its re-use after being separated from ash.
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Life cycle assessment of natural gas fuelled power plants based on chemical looping combustion technology
Energy Conversion and Management, 2019Co-Authors: Alberto Navajas, Francisco García-labiano, Alberto Abad, T. Mendiara, Víctor Goñi, Adrián Jiménez, Luis M. Gandía, Luis F. De DiegoAbstract:Abstract Among the different Carbon Capture and Storage (CCS) technologies being developed in the last decades, Chemical Looping Combustion (CLC) stands out since it allows inherent CO2 capture. In the CLC process, there is a solid oxygen carrier circulating between two Reactors in a cycle that allows providing the oxygen needed for combustion. In one of the Reactors, named as fuel Reactor, the fuel is introduced and combusted while the oxygen carrier reduction takes place. In the second Reactor, named Air Reactor, the oxygen carrier is reoxidized in Air. Different materials based on copper, nickel and iron oxides have been proposed as oxygen carriers for the CLC process. This work presents an environmental evaluation of the CLC process for natural gas based on Life Cycle Assessment (LCA). Five different oxygen carrier materials already tested in pilot plants were considered and the results compared to the conventional natural gas combustion in a gas turbine in a combined cycle without and with CO2 capture using postcombustion capture with amines. In view of the results, lower impact of the CLC process compared to the base case is expected without and with CO2 capture. The influence of several variables on the results was considered, such as temperature in the Air Reactor, lifetime of the oxygen carrier and possibility of recuperation of the depleted oxygen carrier. The nickel-based oxygen carriers were identified as the most adequate to be used in natural gas combustion. However, due to their toxicity, several analyses were also performed in order to identify improvements in the known oxygen carriers that can qualify them to replace nickel-based materials.
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Chemical Looping Combustion of biomass: CLOU experiments with a Cu-Mn mixed oxide
Fuel Processing Technology, 2018Co-Authors: I. Adánez-rubio, Francisco García-labiano, Pilar Gayán, Alberto Abad, T. Mendiara, Maria Izquierdo, Antón Pérez-astray, Luis F. De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion (CLC) is a low-cost CO 2 capture technology with a low energy penalty. Bio-energy with CO 2 capture and storage (BECCS) opens up the possibility for negative CO 2 emissions involving the removal of CO 2 already emitted into the atmosphere. The oxygen needed for combustion in CLC processes is supplied by a solid oxygen carrier circulating between the fuel Reactor and the Air Reactor. In this work, the combustion of different types of biomass, such as pine sawdust, olive stones and almond shells, was studied in a continuous 1.5 kW th CLC unit. A mixed Cu-Mn oxide was used as the oxygen carrier. This material releases gaseous oxygen when reduced, resulting in Chemical looping combustion with oxygen uncoupling (CLOU). The released oxygen reacts with both the volatiles and char generated inside the fuel Reactor when biomass is fed into it. The oxygen carrier is reoxidized in Air inside the Air Reactor. High CO 2 capture and 100% combustion efficiencies were achieved with this Cu-Mn oxygen carrier. The oxygen concentration inside the Air Reactor did not affect CO 2 capture efficiency under the studied conditions.
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Coal combustion with a spray granulated Cu-Mn mixed oxide for the Chemical Looping with Oxygen Uncoupling (CLOU) process
Applied Energy, 2017Co-Authors: Iñaki Adánez-rubio, Francisco García-labiano, Pilar Gayán, Alberto Abad, Luis F. De Diego, Juan AdánezAbstract:Abstract The Chemical Looping with Oxygen Uncoupling (CLOU) process is a form of Chemical Looping Combustion (CLC) technology that enables the combustion of solid fuels by means of oxygen carriers that release gaseous oxygen in the fuel Reactor, i.e. with oxygen uncoupling capability. In recent years, tests have found several Cu-based, Mn-based and mixed oxide oxygen carriers with suitable properties for the CLOU process. Among them, Cu-Mn mixed oxides show high reactivity and high O2 equilibrium concentration at temperatures of interest for coal combustion. In this work, proof of concept was demonstrated by burning coal with Cu-Mn mixed oxides in a 1.5 kWth CLOU unit for the first time. The effect of fuel Reactor temperature, solids circulation flow, fluidization agent in the fuel Reactor (inert N2 or steam as gasifying agent), and excess Air in the Air Reactor on combustion efficiency and CO2 capture rate was analysed. The results showed that high combustion efficiency and CO2 capture are feasible using this material at relatively low fuel Reactor operating temperatures. Therefore, the developed Cu-Mn mixed oxide was a suitable material for use as an oxygen carrier for the CLOU combustion of solid fuels. Optimum operating conditions were determined for this oxygen carrier with regard to the oxygen circulation rate and Air Reactor conditions for the regeneration of the oxygen carrier.
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Sulphur, nitrogen and mercury emissions from coal combustion with CO2 capture in chemical looping with oxygen uncoupling (CLOU)
International Journal of Greenhouse Gas Control, 2016Co-Authors: Raúl Pérez-vega, Francisco García-labiano, Pilar Gayán, Alberto Abad, Maria Izquierdo, Luis F. De Diego, Iñaki Adánez-rubio, Juan AdánezAbstract:Abstract Chemical looping with oxygen uncoupling (CLOU) is a chemical looping combustion (CLC) process for the combustion of solid fuels with the use of a solid oxygen carrier that releases gaseous oxygen inside the fuel Reactor. The aim of this work was to study the fate of pollutant elements present in fuel, i.e. S, N and Hg, during CLOU combustion. Experiments using lignite as fuel were carried out in a 1.5 kW th unit operating continuously for more than 35 h of coal combustion. Novel particles containing 50 wt.% CuO, 10 wt.% Fe 2 O 3 and 40 wt.% MgAl 2 O 4 prepared by spray drying were used as the oxygen carriers in the CLOU process. Most of the sulphur introduced with the fuel exited as SO 2 at the fuel Reactor outlet, although a small amount of SO 2 was measured at the Air Reactor outlet. Most of the nitrogen present in coal was found as N 2 at the outlet of the fuel Reactor, although 20 wt.% of N in the coal was converted to NO. Mercury speciation was also analyzed. The major mercury species in the fuel Reactor was Hg 0 (g), and the Hg 0 (g)/Hg total (g) ratio in the Air Reactor was 0.5.
Anders Lyngfelt - One of the best experts on this subject based on the ideXlab platform.
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Estimating the Solids Circulation Rate in a 100-kW Chemical Looping Combustor
Chemical Engineering Science, 2017Co-Authors: Carl Johan Linderholm, Matthias Schmitz, Anders LyngfeltAbstract:Chemical looping combustion (CLC) is a technology of CO2 capture that can drastically reduce its cost. The solids circulation inside a 100-kW chemical looping combustor was investigated using a novel oxygen carrier called Sinaus by adding fuel batches to the fuel Reactor. The decline and subsequent rise of oxygen concentration in the Air Reactor after each addition was used to determine the residence time of solids in the fuel Reactor and adjacent vessels. The obtained residence time, in combination with the solids inventory, determined the solids circulation for a particular batch experiment. After performing a number of such experiments, the above circulation was correlated with other experimental data, revealing a good correlation between the solids flow at the top of the Air Reactor riser and the actual circulation obtained using batch tests. The relationship between global circulation, , and the mass flow in the Air Reactor riser, (riser), was found to be linear within the investigated interval, being described as = 6.6 + 0.057 (riser). Although this correlation was valid only for the investigated Reactor system, the approach used to obtain the solids circulation could be used to derive a similar correlation for any dual fluidized bed system.
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Chemical-looping combustion with heavy liquid fuels in a 10 kW pilot plant
Fuel Processing Technology, 2017Co-Authors: Patrick Moldenhauer, Magnus Rydén, Tobias Mattisson, Aqil Jamal, Anders LyngfeltAbstract:In this study, chemical-looping combustion was performed with highly viscous vacuum residue. A fuel Reactor with a fuel-injection system for liquid fuels was designed and built for a chemical-looping Reactor with the nominal fuel input of 10 kWth. The gas velocities in the riser section and at the gas-distribution nozzles of this unit are comparable to those of industrial circulating fluidized-bed boilers. Reference experiments were performed with an ilmenite oxygen carrier and two different fuel blends that contained 40 wt.% and respectively 80 wt.% of vacuum residue in fuel oil 1. Fuel conversion was in line with that of experiments from an earlier campaign, where fuel oil 1 was used as fuel. The fuel contained a significant fraction of sulfur, but no SO2 was detected in the flue gas of the Air Reactor. More experiments were performed using an oxygen carrier based on calcium manganite. The oxygen carrier was exposed to fluidization at hot conditions (more than 600°C) for about 95 h, out of which fuel was injected during a total of 9.6 h. Undiluted vacuum residue, fuel oil 1 as well as different blends of these two were used as fuel. Furthermore, the parameters fuel flow, fuel-Reactor temperature and Air flow in the Air Reactor were varied to observe trends in fuel conversion. The experiments were carried out with a fuel flow corresponding to 4.0-6.2 kWth and an oxygen carrier-to-fuel ratio of about 1300-2000 kg/MWth (fuel-Reactor bed mass per thermal fuel-power). With undiluted vacuum residue as fuel and a fuel-Reactor temperature of 1000°C, up to 93% of all carbon leaving the fuel Reactor was in the form of CO2. Carbon leakage from fuel Reactor to Air Reactor was usually below 1% for all fuel types tested, but no SO2 was detected in the off-gas from the Air Reactor. The reactivity of the calcium manganite-based material decreased over the course of the experiments, which is likely due to sulfur poisoning. No defluidization or agglomeration problems were experienced over the course of the experimental campaign.
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Chemical-Looping Combustion of Solid Fuels – What is Needed to Reach Full-Scale?,
2016Co-Authors: Anders Lyngfelt, Tobias Mattisson, Magnus Rydén, Carl Johan LinderholmAbstract:Because the CO2 capture is inherent in chemical-looping combustion (CLC), thus ideally avoiding costly gas separation, this process has a potential for uniquely low costs of CO2 capture. So what is needed to get to the realization of this technology? The purpose of the paper is to discuss the status of the technology, barriers to the implementation of the technology, and also to suggest routes for the critical path from successful testing in small pilots to implementation in commercial-sized units. Thus, operational experiences with oxygen carriers and chemical-looping with solid fuels are discussed, as well as large scale design and important technology challenges. Moreover, possible routes to scale-up are suggested. One way of lowering the costs of intermediate scale-up steps is to build CLC plants without CO2 purification/compression and oxygen production, because CO2 capture normally only makes sense in large scale. Another way to avoid or minimize the cost of the Air Reactor, would be by using a CFBB (circulating fluidized bed boiler) as the Air Reactor. This could either be an existing CFBB which is not in operation or can be taken out of operation for a period, or a designed dual purpose Air Reactor/CFBB where the CFBB can be used as a stand-alone unit after the testing period with CLC.
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operation of a 100kw chemical looping combustor with mexican petroleum coke and cerrejon coal
Applied Energy, 2014Co-Authors: Pontus Markstrom, Carl Johan Linderholm, Anders LyngfeltAbstract:This study describes the design and operation of a 100kW chemical-looping combustor for solid fuels. Six experiments of continuous operation, varying between 8 and 32min in length, have been conducted. The fuels investigated were a Mexican petroleum coke and a bituminous coal from Cerrejon in Colombia. Overall, it was found that operation was stable and loss of char to the Air Reactor was small, meaning that the CO2 capture efficiency was high (up to 90% at temperatures close to 950°C in the fuel Reactor). Gas concentration measurements showed the presence of unconverted CO, H2 and CH4 corresponding to an oxygen demand of around 20%, depending on the fuel Reactor temperature. In addition, a residence-time analysis was conducted from a batch experiment, enabling an estimation of the mass flow of oxygen carriers through the system using the riser pressure drop in the Air Reactor.
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CHEMICAL-LOOPING COMBUSTION IN A 100 KW UNIT FOR SOLID FUELS
2012Co-Authors: Pontus Markstrom, Anders Lyngfelt, Carl Johan LinderholmAbstract:Chemical-looping combustion is a novel technology for combustion of fossil fuels. By using a circulating bed material to transfer oxygen to the fuel, a pure stream of CO2 can be obtained from the flue gas, undiluted by N2 from the Air. The main advantage of this capture technology is that there is no direct efficiency loss in obtaining the CO2 in a separate stream. This study describes results from operation in a 100 kWth chemical-looping combustor for solid fuels. The oxygen carrier used was ilmenite, an iron-titanium oxide. Coal is fed directly into a loop seal, leading to the fuel Reactor, through a set of screws. All parts of the unit are fluidized with steam, except for the Air Reactor, which is fluidized with Air, and the loop seal with the fuel insertion, which is fluidized with nitrogen. All-in-all, the unit has eleven windboxes, of which four are loop seals. Three experiments have been conducted using a Colombian coal as fuel. Operation was stable and loss of char to the Air Reactor was small, meaning that the CO2 capture efficiency was high (>90%). Gas concentration measurements showed the presence of unconverted CO, H2 and CH4 corresponding to an oxygen demand of 18.5% at 950°C.
